Case Study

Case Study

The patient is an 86-year-old presenting with delirium. Her comorbidities include hypertension, chronic kidney disease, gastroesophageal reflux disease, and atrial fibrillation. Based on this history, the factor that might influence the patient’s pharmacokinetic and pharmacodynamics processes is age.

According to Thürmann (2020), advanced age impacts the absorption, distribution, metabolism, and excretion of drugs. Age-related effects that affect absorption include reduced gastric emptying, splanchnic blood supply, and changes in the secretion of gastric acid (Drenth-van Maanen et al., 2020). Findings have demonstrated that aging reduces the absorption of drugs containing iron and calcium (Thürmann, 2020). Additionally, the absorption of vitamin B12 is reduced (Thürmann, 2020). Aging is associated with changes in the total body water and fat distribution. This is demonstrated by an increase in total body fat and a decrease in total body water. Accordingly, polar drugs such as digoxin have a low volume of distribution, hence high serum concentration (Thürmann, 2020). This increases the risk of toxicity. Non-polar drugs such as diazepam have a high volume of distribution in the elderly (Thürmann, 2020). Do you need urgent assignment help ? Our homework help will save you tons of energy and time required for your homework paper.

According to Thürmann (2020), aging is associated with a decrease in hepatic mass, hepatic blood flow, and function. This affects the metabolism and bioavailability of drugs. Findings demonstrate an age-related decrease in the metabolism of drugs. Notably, phase 1 metabolism reactions are impeded (Thürmann, 2020). This can reduce and delay the activation of prodrugs such as omeprazole and enalapril (Thürmann, 2020). Conversely, the bioavailability of drugs that undergo significant first-pass metabolism, such as metoprolol, is increased, hence the risk of toxicity (Thürmann, 2020). Renal function is decreased with advanced age. The glomerular filtration rate is lowered, and so is the clearance of drugs. This increases the toxicity of these drugs. Notably, the adverse effects of drugs with a narrow therapeutic index, such as digoxin, are significantly elevated (Shikdar et al., 2022).

The pharmacodynamics changes correspond to changes in pharmacokinetics. For example, a reduction in glomerular filtration rate and the associated increase in the concentration of drugs such as digoxin increases its pharmacodynamics (Thürmann, 2020). Accordingly, digoxin toxicity occurs. A decrease in hepatic function and the associated decrease in the activation of prodrugs lowers their pharmacodynamics acid (Drenth-van Maanen et al., 2020).

Pharmacokinetic and Pharmacodynamic Changes Versus Recommended Drug Therapy

Age-related changes in pharmacokinetic and pharmacodynamic processes impact the recommended drug therapy. For instance, age-related reduction in the glomerular filtration rate is associated with reduced drug clearance and drug toxicity (Thürmann, 2020). In this scenario, the dosage of drugs should be reduced to avert the possibility of adverse effects. This is particularly relevant for drugs with a narrow therapeutic index, such as digoxin (Shikdar et al., 2022). Additionally, an age-related decrease in hepatic metabolism can reduce the activation of prodrugs and lower their activity. The selection of alternative drugs or dose modification can help to avert this. An example in this scenario is the substitution of omeprazole (a prodrug) with metoclopramide (Thürmann, 2020). Furthermore, the patient’s dosage of metoprolol and warfarin should be reduced because the decrease in renal and hepatic function increases the risk of their toxicity (Shikdar et al., 2022; Thürmann, 2020).

Improvement of the Patient’s Drug Therapy Plan

Modifications in the dosages of the drugs can improve that treatment plan. The dosage of warfarin should be reduced to 2 mg. This is relevant because the patient’s INR of 3.8 is higher than the recommended range of 2 to 3 for patients on anticoagulation therapy (Shikdar et al., 2022). An INR of 3.8 increases the risk of bleeding (Shikdar et al., 2022). The dose of metoprolol should be maintained at 25mg, but the tartrate salt that doesn’t provide an extended-release profile should be adopted (Peeters et al., 2019). This will be beneficial because the patient’s blood pressure of 101/58 and heart rate of 53 could predispose the patient to hypotension (Peeters et al., 2019). These readings may be caused by the extended-release formulation and drug accumulation due to reduced clearance and metabolism. I would maintain the dose of omeprazole at 40 mg and monitor the patient after 4 weeks for any changes. I would maintain the multivitamins in the treatment plan. The dosage of acetaminophen should be reduced to 500mg TID to reduce the risk of liver damage. This is relevant for this patient because age is associated with a reduction in liver function (Thürmann, 2020).

References

Drenth-van Maanen, A. C., Wilting, I., & Jansen, P. A. F. (2020). Prescribing medicines to older people—How to consider the impact of aging on human organs and body functions. British Journal of Clinical Pharmacology, 86(10), 1921–1930. https://doi.org/10.1111/bcp.14094

Peeters, L. E. J., Kester, M. P., Feyz, L., Van Den Bemt, P. M. L. A., Koch, B. C. P., Van Gelder, T., & Versmissen, J. (2019). Pharmacokinetic and Pharmacodynamic Considerations in the Treatment of the Elderly Patient with Hypertension. Expert Opinion on Drug Metabolism and Toxicology, 15(4), 287–297. https://doi.org/10.1080/17425255.2019.1588249

Shikdar, S., Vashisht, R., Bhattacharya, P. T. (2022). International Normalized Ratio (INR). https://www.ncbi.nlm.nih.gov/books/NBK507707/

Thürmann, P. A. (2020). Pharmacodynamics and Pharmacokinetics in Older Adults. Current Opinion in Anaesthesiology, 33(1), 109–113. https://doi.org/10.1097/ACO.0000000000000814

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The following is the case that should be used for your assignment:

LM is an 86-year-old female admitted to the emergency department with delirium. Her spouse is with her and verifies that LM adheres to the medications she is currently prescribed. She does not self-monitor her BP or heart rate at home.

Case Study

PMH:

A Fib diagnosed 1 month ago
HTN x 10 years
CKD x 5 years
Osteoarthritis x 7 years
GERD x 20 years
Medications:

Digoxin 0.25 mg QD
Metoprolol XL 25mg QD
Warfarin 3 mg QD
APAP 650 mg TID
Omeprazole 20mg QD
Multivitamin QD
Allergies: NKDA

Social History:

Married to husband for 57 years
No smoking, alcohol, limited daily exercise (short walks each morning)
Family History:

None reported

Vitals: Labs:

Wt 113 lbs Ht 5’4” Na+ 138 K+ 4.0

BP 101/58, HR 52 Cl- 99 CO2 27

BUN 33 Cr 1.2

Gluc 109 INR 3.8

Dig 2.4

PE:

Elderly female with altered level of consciousness, no signs of bruising, bleeding, or other injury.

Write a 2- to 3-page paper that addresses the following:

Explain how the factor you selected might influence the pharmacokinetic and pharmacodynamic processes in the patient from the case study you were assigned.
Describe how changes in the processes might impact the patient’s recommended drug therapy. Be specific and provide examples.
Explain how you might improve the patient’s drug therapy plan and explain why you would make these recommended improvements.